Hi,
I am having problem solving this question - could anyone explain??
Solution Y is 30 percent liquid X and 70 percent water. If 2 kilograms of water evaporate from 8 kilograms of solution Y and 2 kilograms of solution Y are added to the remaining 6 kilograms of liquid, what percent of this new solution is liquid X?
(A) 30%
(B) 33 1/3%
(C) 37 1/2%
(D) 40%
(E) 50%
500 PS
This topic has expert replies
Hi, I'm not sure if the following is the most efficient way to do it. At least for me it was quick to do this way!
in solution Y = 30% x + 70% w(ater)
So, in 8kg of Y = 2.4x + 5.6w
from this 2kg water is removed (Evaporated) so, in the remaining
6kg Y = 2.4x + 3.6w.
Now 2kg Y is added, which has 0.6x + 1.4w. So,
6kg Y = 2.4x + 3.6w.
2kg Y = 0.6x + 1.4w
-------------------------
8kg Y = 3.0x + 5.0 w
x = 3/8 * 100 = 37.5%
Answer is C
in solution Y = 30% x + 70% w(ater)
So, in 8kg of Y = 2.4x + 5.6w
from this 2kg water is removed (Evaporated) so, in the remaining
6kg Y = 2.4x + 3.6w.
Now 2kg Y is added, which has 0.6x + 1.4w. So,
6kg Y = 2.4x + 3.6w.
2kg Y = 0.6x + 1.4w
-------------------------
8kg Y = 3.0x + 5.0 w
x = 3/8 * 100 = 37.5%
Answer is C
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solution Y contains 30% (i.e 0.3) liquid X and 70% (0.7) water.
8kg of solution Y will contain = 30% liquid X in 8kg + 70% water in 8kg
=0.3 (8) kg liquid + 0.7(8) kg water
= 2.4 kg liquid X + 5.6 kg of water
Now, if 2 kg water evaporates from 8 kg of Y, we have
= 2.4 kg liquid X + (5.6-2) kg of water left.
= 2.4 kg liquid X + 3.6 kg of water
=6 kg of Y
2 kg of Y will contain,
= 30% liquid X in 2 kg + 70% of water in 2 kg
=0.3(2) kg liquid X + 0.7(2) kg water
= 0.6 kg liquid X + 1.4 kg water
Adding this to the liquid we have left, we now have = (2.4 + 0.6) kg liquid X + (3.6+1.4) kg water
=3 kg liquid X + 5 kg water
=8 kg of liquid
percentage of liquid X= $$\frac{3kg}{8kg}\cdot100\%\ =\ 37\ \frac{1}{2}\%$$ .
Hence, the correct option is C
8kg of solution Y will contain = 30% liquid X in 8kg + 70% water in 8kg
=0.3 (8) kg liquid + 0.7(8) kg water
= 2.4 kg liquid X + 5.6 kg of water
Now, if 2 kg water evaporates from 8 kg of Y, we have
= 2.4 kg liquid X + (5.6-2) kg of water left.
= 2.4 kg liquid X + 3.6 kg of water
=6 kg of Y
2 kg of Y will contain,
= 30% liquid X in 2 kg + 70% of water in 2 kg
=0.3(2) kg liquid X + 0.7(2) kg water
= 0.6 kg liquid X + 1.4 kg water
Adding this to the liquid we have left, we now have = (2.4 + 0.6) kg liquid X + (3.6+1.4) kg water
=3 kg liquid X + 5 kg water
=8 kg of liquid
percentage of liquid X= $$\frac{3kg}{8kg}\cdot100\%\ =\ 37\ \frac{1}{2}\%$$ .
Hence, the correct option is C
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dunkin77 wrote:Hi,
I am having problem solving this question - could anyone explain??
Solution Y is 30 percent liquid X and 70 percent water. If 2 kilograms of water evaporate from 8 kilograms of solution Y and 2 kilograms of solution Y are added to the remaining 6 kilograms of liquid, what percent of this new solution is liquid X?
(A) 30%
(B) 33 1/3%
(C) 37 1/2%
(D) 40%
(E) 50%
Originally, solution Y has 0.3 x 8 = 2.4 kg of liquid X and 0.7 x 8 = 5.6 kg of water. After 2 kg of water evaporate, solution Y has 2.4 kg of liquid X and 3.6 kg of water. However, since 2 kg of solution Y (of which, 0.3 x 2 = 0.6 kg is liquid X and 0.7 x 2 = 1.4 kg is water) are added back to the remaining 6 kilograms of solution Y, solution Y now has 2.4 + 0.6 = 3 kg of liquid X and 3.6 + 1.4 = 5 kg of water). Therefore, the percent of the new solution is liquid X is 3/(3 + 5) = 3/8 = 37.5%.
Answer: C
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